Depends on time of the year what a big quake will do, if it hits when the ground is dry and solid it will be different than when the ground is saturated with water. A really big quake will bring down most old buildings but the new ones are built to withstand quakes. I helped build the Corvallis hospital and they said it was designed to be quake proof.
As far as guns and the government taking them to get into the shelter, just hide it outside the shelter.
As far as guns and the government taking them to get into the shelter, just hide it outside the shelter.